Abstract B42: Modeling MDS in mice through precise molecular lesions in APC and mDia1.

Abstract

Abstract While the murine equivalent to “5q– syndrome” should map to the distal arms of murine chromosomes 11 and 18, molecular attempts have been unsuccessful in generating a reliable mouse model of myelodysplasia leading to exacerbated myeloid leukemia. Genetic studies suggest interactions between individual proteins in this locus suppress tumor initiation. More specifically, cellular and biochemical studies demonstrated collaboration between two proteins in the commonly deleted regions of 5q– syndrome: mDia1 (mammalian Diaphanous-related Rho GTPase effector formin) and APC (adenomatous polypolis coli). Therefore, we generated mice compounding these two putative disease alleles. Because both mDia1 knockout [Drf1(–/–)] mice and Apcmin (min = multiple intestinal neoplasia; haploinsufficient) mice develop age-dependent myelodysplastic syndrome (MDS), we hypothesized that a mouse strain lacking both proteins will exhibit a more severe MDS phenotype than either mutant allele alone. To define the disease caused by mutation in Drf1 and Apcmin, we monitored erythropoiesis, myelopoiesis, and overall survival. At all ages, mice with both mutant alleles exhibit granulocytosis. Anemia occurs in aged mice (>270 days), exhibiting drastic differences in blood cell morphology that corresponded to differences in long-term survival in comparison to either Drf1–/– or Apcmin animals. Furthermore, immunophenotyping of all subpopulations indicate an accumulation of CD71+/TER-119+ cells in mice with both mutant alleles, however no significant differences in CD11b expression appeared among CD45+ bone marrow subpopulations. Our studies indicate that combined loss of mDia1 and APC expression and function direct disease progression. We are currently defining the hematopoietic precursor cell responsible for anemia and bone marrow failure. This enhanced mouse model also serves as molecular laboratory to study disease progression and to test potential therapeutics under development in our laboratory. Citation Format: Julie Davis Turner, Susan Kitchen-Goosen, Andrew M. Howard, Heather Schumacher, Art S. Alberts. Modeling MDS in mice through precise molecular lesions in APC and mDia1. [abstract]. In: Proceedings of the AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(17 Suppl):Abstract nr B42.